The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Neural stimulation is typically the process of using an external source to activate ion channels causing depolarization of the neural membrane and evoking an action potential to propagate down the axon of a stimulated neuron. Electrical, thermal, chemical, optical and mechanical methods have been reported to generate action potentials in both the central nervous system (CNS) and peripheral nervous system (PNS) [B1]. Electrical stimulation has been the gold standard for the stimulation of neurons for both clinical and basic research applications. For nearly two centuries, neurons have been activated by electrical stimulation through the injection of a current or change in voltage delivered via an electrode placed on or near the neural tissue. The injected current or change in voltage causes an increase in the transmembrane potential to activate voltage-gated ion channels which generates action potential propagation down the neuron's axon [B2-5]. However, electrical stimulation can have limited spatial precision due to inherent electrical field spread which can recruit unwanted neural tissue, and electrical stimulation results in a stimulation artifact which can mask relevant neuronal signals resulting from the stimulation event [B6, 7].